In the summer of 1947, John Harper and his girlfriend Jill are driving along the south coast on their way to lectures at Brighton Art College. Suddenly, a forbidding black cloud moves in from the sea and envelopes them, leaving them powerless to escape. Actually an immense area of gravitation, the malevolent mass has the effect of transporting Jill back to 1887. Bewildered and alone, Jill must now make a life for herself. Desperately wanting to return home, she must also be careful to maintain the secrecy of her past - especially in a strict society where 'madness' can lead to incarceration. Her sanity is barely preserved by the friendship of a local minister's wife. When Jill meets handsome and wealthy landowner Mr Gregson, it is clear he has one thing on his mind: her hand in marriage. Despite everything, she cannot help growing fond of him. With seemingly no way of returning home or being reunited with John, and with a luxurious lifestyle on offer, she accepts his proposal. But when all finally seems to be falling into place, she is suddenly given an opportunity to return to 1947 - and her first love...